Reaction wheel assemblies (RWA) are well-known major sources of microvibrations, whilst they have been studied thoroughly and many disturbance types can be reasonably modelled, bearing disturbances and how their amplitude evolves with the RWA rotational speed are not at the same level of confidence. Whilst studies have been carried out, many of the test rigs used do not truly show the bearing harmonic development, either due to interference from other disturbances such as structural modes or are not representative of an RWA. This study aims to design and validate a test rig which alleviates those issues by moving the resonance frequencies out of a range of interest and isolating the motor disturbances. Using this test rig, it was possible to observe many engine order development without any inference and start to investigate some of the effects some manufacturing parameters can have. The two studied and discussed in this paper were the effect of reassembly and static unbalance. Investigating the microvibration signature at different levels ranging from a top-down to individual harmonics it showed a clear significant variation between disturbance amplitudes.